I am a big fan of Edgar Schein and his new book, Humble Inquiry: The Gentle Art of Asking Instead of Telling, is an excellent read and highly recommend it. However, I believe that you will be better prepared if you read Schein’s previous book on Helping: How to Offer, Give, and Receive Help. A video about his book follows.
Schein’s books are vey applicable to most sales and marketing people. I think you will find that his approach will assist you greatly in your customer conversations both online and offline. Few “experts” cover the range of material that his ideas can apply to as well as what Schein does with his. Schein is the real thing.